Need help working bugs out of SRT setup!

[Daine]

Thank you!!

Thats what I thought also from all the videos I have seen.. Glad I didn't have to feel stupid LMBO!

I pressed dual ball bearings and it is probably overly free as the bearing were higher quality and not just a brass bushing... My slick pin pivot I made is made from 303 stainless and polished. I know its all about friction but it was my first uneducated attempt and I had to decide if a rough finish would frey the rope over time.. I figured the bend the wrench supplied might suffice enough friction and so I polished the pin first if it doesn't work then I will rough it up some to create more friction to mimic the galvanized or zinc finish on the OEM slic pin???..

 

[Reach]

Thank you!!

Thats what I thought also from all the videos I have seen.. Glad I didn't have to feel stupid LMBO!

I pressed dual ball bearings and it is probably overly free as the bearing were higher quality and not just a brass bushing... My slick pin pivot I made is made from 303 stainless and polished. I know its all about friction but it was my first uneducated attempt and I had to decide if a rough finish would frey the rope over time.. I figured the bend the wrench supplied might suffice enough friction and so I polished the pin first if it doesn't work then I will rough it up some to create more friction to mimic the galvanized or zinc finish on the OEM slic pin???..

The stock version has what appears to be a machined stainless slic pin, with a slightly rough finish, similar to what you get out of a glass beader. It polished itself with use though, so I don’t see polishing it as a problem. My best guess as to the problem is not friction, but possible the distance and/or angles between the tether, pulley, and pin. Pulley diameter could also cause problems.

Different rope and hitch cord combinations make a difference too, I find “grabby” hitch cords tend to lock up on me, as I’m a bit of a bigger guy, so I prefer a slightly larger hitch cord diameter.

 

[Jonny]

Do you have other hitch cord besides the GM stuff? It’s Chinese? Try epicord, Ocean, BeeLine, or HRC, it might be night and day difference. You don’t need to shell out for eye splices, you can get a lot of different hand tied cords for 40$. I think Wesspur sells a sampler pack too.

 

[Tom Lynch]

I'm echoing what has already been said. The positions and distance (and to a lesser extent diameters) for the pin to the roller, as well as the position of where the tether is in relation (both X & Y). The friction of the pin and pulley should have a lesser influence. The friction comes more from the bend, in my understanding (guess). Overall your clone does indeed look close.

Also if that hitch cord and rope aren't to the industry standards, that will really mess with the characteristics. If it is the hitch cord I suspect, from amazon and the rope perhaps dynamic rock climbing dia. 9-10mm? You may want to confirm what cordage you are working with, before reworking the rope wrench.

My thoughts on working this problem out would be to single out each element.
A test would be to see just how much force it takes to move the wrench on a weighted rope. Suspend the rope with the wrench, tether and pulley in line, no friction hitch. Then add tension, hang a wight around 150-200lbs. Then pull down on the wrench, it should provide around 70lbs of resistance? I somewhat recall the wrench should take about 40% of the load?

 

[DSMc]

First thing, try some different, thicker climbing line, like Yale 11.7 stuff.

 

[islandarb]

Yo bro this vid might help. Great work on pully and wrench. The bend when wrench is engaged is about 95*. Degrees. If you need more info let me know. I a. Over 8 years on a wrench. Know it inside and out. Gave my first homemade wrench to a dude years ago @oceans gave it to me. Worked like a charm. Yours looks good. Rope and hitch and tether is your peob I believe.

 

[Daine]

Swingdude.... ABSOLUTELY THANK YOU!!! Great help!

 

[islandarb]

Swingdude.... ABSOLUTELY THANK YOU!!! Great help!

This gave you something to work with?

 

[Daine]

Absolutely!
My tether is 12" and my E2E is 30"

I was going to run a VT but it just locks up and I won't release until I unweight the rig.. If I slightly weight the rig again it will lock the prusik and I can not descend.

I will weight the wrench and show the angles I achieve and see what weigh reduction I get from my wrench...

I think you and others are correct. I think it may be with the tether length and or the type of hitch prusik or the hitch line itself.

I will definetly test all of this tomorrow and post back with photos or video of the results..

I am certain this will help others!!!

 

[rico]

Absolutely!
My tether is 12" and my E2E is 30"

I was going to run a VT but it just locks up and I won't release until I unweight the rig.. If I slightly weight the rig again it will lock the prusik and I can not descend.

I will weight the wrench and show the angles I achieve and see what weigh reduction I get from my wrench...

I think you and others are correct. I think it may be with the tether length and or the type of hitch prusik or the hitch line itself.

I will definetly test all of this tomorrow and post back with photos or video of the results..

I am certain this will help others!!!

Do not underestimate the importance of the rubber grommet to help initiate the activation of the wrench.. Especially on a longer tether......
A larger climbing line could also make a world of difference.....

 

[Brocky]

For some reason your Wrench isn’t rotating enough. As swing stated it should be more like 90 degree angle, rather than the 45 shown in your picture. It looks like there isn’t enough sideways distance between the top pin and bottom pulley, they may be too close to being inline.
Agree with using a shorter hitch, but not sure a larger diameter rope would improve things as the are.

@swingdude, the hitch in your vid is a Coopers, adding a braid in front helps to keep the twist part centered in the back.

 

[islandarb]

For some reason your Wrench isn’t rotating enough. As swing stated it should be more like 90 degree angle, rather than the 45 shown in your picture. It looks like there isn’t enough sideways distance between the top pin and bottom pulley, they may be too close to being inline.
Agree with using a shorter hitch, but not sure a larger diameter rope would improve things as the are.

@swingdude, the hitch in your vid is a Coopers, adding a braid in front helps to keep the twist part centered in the back.

Well I know Sam well so must have had it in my brain long ago.....I throw a braid in if the prussic needs it. But I love loose hitches. Hate tight binding fuckers.

 

[Birdyman88]

@Daine I'm gonna take a stab here. First rubber grommet and optimal hitch cord are crucial. BUT, I notice that the eye on you tether that connects to wrench has 1) a large eye and 2) a small pin. If there is too much play between pin and eye, the hitch could be starting to grab before the pin engages the wrench causing the hitch to be fully engaged before the wrench gets engaged.

I know a lot of us out here have really good results with a michoacan, and a high temp cord though. That polyester GM cord in a VT might just be biting too hard and too fast.

 

[climbstihl]

I agree you should try to determine if your hitch works in a DdRT fashion. I also have a GM 30" 8mm hitch cord, I don't use it anymore because it doesn't work well and I'm not sure I trust it. It doesn't work with any other hitch than a VT, and it is very grabby. You should definitely get something better.
I believe the 40% the RW are supposed to take off the hitch are incorrect, I remember more like 65%. That's also more what it feels like, the hitch is easier to break than in DdRT with the RW. With my old DIY RW, it was more like 50%, and the angle it breaks the rope at is far less than the regular RW. So I'm not sure it's the angle with yours, I think it might be the diameter of your rope.

 

[JeffGu]

A shorter tether might help, with those angles. And stiffer. You can stiffen it up with double-wall, adhesive-lined shrink tubing.

 

[megadosevitaminc]

I got one of those gm prusiks too. I quit using it. Something about it freaks me out. Doesnt seem real great quality.

 

[oceans]

Gave my first homemade wrench to a dude years ago @oceans gave it to me. Worked like a charm....

Cheese on bread! I forgot about that thing! You just gave me a good laugh bud! Hope you’re well.

 

[Daine]

Okay guys, I'm sorry I haven't posted back sooner but it has rained here ever since I started this thread. Today was the only clear dry day I could test out the gear!

Well, I figured out the issue and a few of you were on track. .... THE FRICTION!!!

I put very good ball bearing in my pulley. I think I am VERY close to the original with my pin placement, so I knew it wasn't exactly ALL the issue. Maybe a small percent though!

I took the pulley out and machined a new one this time with only a pilot hole. I also used a semi tight fit over the pivot bolt. I could turn the pulley with my fingers but with slight resistance.

Worked like a charm!!!

Why I think the difference with the original?? Well I think when pressure or weight is put on the original, it likely loads the pulley so it doesn't turn so easy. The more the weight is applied the steeper the angle the more it loads the pulley. Thus you achieve that 90* angle with the rope before the RW slides and engages the prusik!

I'm going to increase the slick pin size in order to push the rope closer to the pulley further increasing the rope angle in theory. I'll try it for kicks to see if that helps even more. However what I've achieved is pretty dang good!

Right now it feels like it is taking about 60% or more off the hitch. The mohichican <---- sorry spelling?? Was just friggin awesom! I tried the VT, VT X, the blakes, the Knut, and a couple more.

The VT just locks up with this prusik rope combo!

A couple hitches worked almost as good but not as good as the mohichican!

I'm sorry to go against what you guys said but that GM hitch locked and released like butter! My first time I shot up the tree like nothing!

Came down as slow or fast is I wanted. NO LOCK UP! The hitch did not fail to lock and was completely controllable! No complaints!!

It is to long! I need a 28" but an extra wrap does okay!

Not knowing what awesome gear feels like, I can't compare or give solid feedback. I think it is a testimony however when a complete noob "ME" can report back with this such a positive result.

I'm sure there are more I can improve on with the RW. Like installing the rubber bumper which I'm in the process of doing. I am going to post back with either a video or photos with my results.

To anyone attempting to build a rope wrench DO NOT USE BEARINGS!!

I also don't think the tether has a significant effect at all. I did try a temporary shorter makeshift tether and there were negligible difference!


If anyone is interested I could post up a schematic drawing with how I went about it.

THANK YOU ALL!

 

[Burrapeg]

. . . To anyone attempting to build a rope wrench DO NOT USE BEARINGS!! . . .

I eventually modified my DIY RW with two equal bollards bolted solid, so they can't turn at all. And they are both turned to a concave profile to fit the diameter of the rope. Works a treat now and no flattening of the rope at all.